Programmable logic devices (PLDs) (e.g., field programmable gate arrays (FPGAs)), complex programmable logic devices (CPLDs), field programmable system on a chips (FPSCs), or other types of electronic devices) may be implemented as part of an electronic assembly that is “hotswapped” by being plugged into a live power supply, such as a backplane. Typically, the electronic assembly has various capacitive components, such as an array of filters, bypass, and hold-up capacitors. The combined capacitive load of the capacitive components may act like a momentary short circuit when the electronic assembly is plugged in. If left unchecked, the in-rush current from the live power supply may damage certain components of the electronic assembly or cause power disruption to other devices connected at the backplane or power supply.
Typically, the hotswap device utilizes a transistor, such as a metal-oxide semiconductor field-effect transistor (MOSFET), to limit the in-rush current. In particular, during hotswap, the gate of a power MOSFET is slowly charged up from the power supply. The power MOSFET acts as a solid state switch to limit the in-rush current. However, the MOSFET needs to be selected and/or sized such that the maximum current and maximum voltage drop across drain to source do not exceed the safe operation area (SOA) of the MOSFET. This may result in an oversized power MOSFET that takes up space and is more costly.
Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.